docs: def get_attr_desc(instance, attribute, action):
      """
      Fetch the appropriate descriptor for the attribute.
  
      :param instance: Model instance
      :param attribute: Name of the attribute
      :param action: AttributeAction
      """
      descs = instance.__jsonapi_attribute_descriptors__.get(attribute, {})
      if action == AttributeActions.GET:
          check_permission(instance, attribute, Permissions.VIEW)
          return descs.get(action, lambda x: getattr(x, attribute))
      check_permission(instance, attribute, Permissions.EDIT)
      return descs.get(action, lambda x, v: setattr(x, attribute, v))